Liquid oxygen explosive composition process and apparatus



May 22, 1962 L. P. BARLOW 3,

LIQUID OXYGEN EXPLOSIVE COMPOSITION PROCESS AND APPARATUS Filed Sept. 16, 1957 2 Sheets$heet 1 INVENTOR [ester-1 Barlow ATTORNEYS L. P. BARLOW May 22, 1962 LIQUID OXYGEN EXPLOSIVE COMPOSITION PROCESS AND APPARATUS Filed Sept. 16, 1957 2 Sheets-Sheet 2 S R w mw Wz w I A B w 5 a a w m .r 51 31;: 7 w M 1: l i u 3,035,519 LIQUID OXYGEN EXPLOSIVE COMPOSITION PROCESS APPARATU Lester P. Barlow, Stamford, Conn., assignor to Atlas Chemical Industries, Inc., a corporation of Delaware Filed Sept. 16, 1957, Ser. No. 684,225 13 Claims. (Cl. 102-43) The present invention relates to explosive composition and methods and apparatus for loading explosives in blast holes.

The use of liquid oxygen-combustible material explosives for commercial blasting operations such as those involved in mining open cut excavations, submarine operations and the like have been known. In my Patent No. 2,704,515 issued March 22, 1955, I have disclosed the use of such LOX explosives wherein a blast hole is drilled, the hole partially filled 'with the mixture of combustible material and a liquified inert gas having a boiling point preferably no higher than that of oxygen, such as nitrogen, the nitrogen permitted to vaporize with the accompanying freezing of the ground around the blast hole and liquid oxygen subsequently introduced into the blast hole.

In this method of preparing blast holes, it has been found that a great excess of liquified inert gas in proportion to combustible material, such as a great excess of liquid nitrogen with respect to carbon, causes the carbon particles in the mixture to orient in a flat position and settle into a packed dense mass at the bottom of the blast hole. This packing of the carbon particles reduces the amount of the liquid oxygen which can be subsequently introduced into the carbon mass. Thus the effective contact between the components of the explosives is reduced and the explosive efliciency and shattering effect reduced.

In commercial blasting operations involving LOX explosives as in blasting taconite ore, a number of spaced holes are filled one after the other with the components of the LOX explosives. Since all of the charges will be exploded simultaneously, it is desirable to reduce the time required for loading all of the blast holes. Generally, in the prior processes of preparing a blast hole, a mixture of a liquified inert gas, such as nitrogen and carbon, is first introduced into the hole and the nitrogen permitted to evaporate substantially completely before introducing liquid oxygen. The time required for volatilization of the liquid nitrogen in all of the holes, filled one after the other, has considerably prolonged the time required for filling a series of blast holes.

Further, after filling a series of blast holes with LOX explosives, there has been no practical way of determininrn how much liquid oxygen remains in the holes filled at the beginning of the series from which oxygen has been evaporating for the longest time. If so much oxygen has evaporated from these blast holes as to cause cushioning air spaces to be formed in the blast hole with resultant reduction of explosive efliciency and resultant inadequate amount of oxygen to combine with the combustible material, such as carbon, in the hole, it would be necessary to insert additional liquid oxygen into these holes. However, no practical way has been provided for determining the quantity of liquid oxygen remaining in the blast holes after some time has elapsed after preparing that blast hole. In the above-described methods of preparing a blast hole with a LOX explosive, it has been generally customary to insert a loading tube in the blast hole, introduce a mixture of liquified inert gas and combustible material, and pack the portion of the hole around the loading tube with loose gravel for a partial seal having blow-holes therethrough. It has also been proposed to provide a filter above the mixture. Thus, evapo- 3,35,5l9 Patented May 22, 1962 rating liquified inert gas and subsequently evaporating oxygen pass directly upwardly along the sides of the blast holes and through the blast holes or filter and the loose gravel to the atmosphere. It has been found that this passage of volatilized inert gas and gaseous oxygen directly upwardly adjacent the side of the blast hole causes a displacement of carbon particles inwardly and the formation of gas bubbles adjacent the side of the blast hole, providing a resultant cushioning effect of the explosion and reduction of the shattering force thereof.

I have found, however, that employing the features of the invention, these problems and disadvantages can be largely eliminated.

I have now discovered that if certain proportions of liquified inert gas and combustible material are used wherein there are about 2.5 to about 3 parts by weight of liquified inert gas to one part by weight of combustible material that the combustible material such as carbon remains loose and fluffy. Thus, after the liquified inert gas has evaporated, a greater quantity of liquid oxygen can be introduced into the loose mass of combustible material.

I have further discovered that if, in filling a blast hole with LOX explosives, after the mixture of liquified inert gas and combustible material has been introduced into the blast hole, freezable material is introduced into the blast hole between the loading tube and the side of the hole, to provide an imperforate frozen seal impervious to the passage of gas and liquid, the evaporating gases pass inwardly to the loading tube and upwardly therein, avoiding the displacement of combustible material particles and formation of gas bubbles adjacent the side of the blast hole.

Further, according to the invention, novel apparatus is provided for introducing the components of the LOX explosive into the blast hole. This apparatus includes a hollow conduit to be inserted in the blast hole having a rigid upper portion that is liquid and gas impervious and a lower portion that is liquid and gas pervious and solid impervious. The lower portion is a filter which may be in the form of a canvas bag to permit the escape of evaporating inert gas and the passage of liquid oxygen While preventing the flow of combustible material particles out of the blast hole. Where the filter is a flexible canvas bag, a reinforcing member is provided which may take the form of a coil spring positioned Within the bag. In order to further strengthen the hollow conduit to maintain its shape when the mixture of liquified inert gas and combustible material is being introduced into the blast hole, a removable staff is provided within the hollow conduit.

For the introduction of liquid oxygen into the blast hole and the removal of volatilized inert gas, the invention provides an apparatus including a hollow conduit extending down into the blast hole, a concentric hollow duct extending within the conduit down to the bottom of the conduit and having an opening at its lower end, a conainer for liquid oxygen having an outlet aperture sealed to the upper edge of the hollow conduit, and a funnel sealed to the upper edge of the hollow duct and positioned Within the container.

It is accordingly a primary object of the invention to provide a method of loading a blast hole with LOX explosives.

It is a further object of the invention to provide a method of loading a blast hole with LOX explosives wherein the blast hole is preliminarily frozen by the introduction of a mixture of liquified inert gas and combustible material, and the inert gas rapidly removed simultaneously with the introduction of liquid oxygen.

It is a further object of the invention to provide a method of loading a blast hole by introducing a properly proportioned mixture of inert liquid gas and combustible material so that the combustible material will remain loose and will not pack into a dense mass.

It is another object of the invention to provide a method of loading a blast hole with LOX explosives wherein a gas-tight seal is provided above a mixture of liquified inert gas and combustible material to prevent passage of volatilized gas upwardly along the side of the hole.

A further object of the invention is to provide apparatus for simultaneously permitting escape of volatilized inert gas from the blast hole and the introduction of liquid oxygen into a blast hole for LOX explosives.

A further object of the invention is to provide an apparatus for loading a blast hole with LOX explosives wherein the amount of liquid oxygen in the blast hole may be determined by observing the liquid oxygen in a container above the hole.

A further object of the invention is to provide a composition for loading a blast hole comprising critical proportions of a liquified inert gas and a combustible material.

Further objects and advantages of the invention will become apparent upon reference to the following specification and claims and appended drawings wherein:

FIGURE 1 is a vertical section VlfiW of a blast hole after loading has been partially completed with a mixture of liquified inert gas and combustible material according to the invention;

FIGURE 2 is a horizontal section taken along the line 2-2 of FIGURE 1;

FIGURE 3 is a vertical section view of a blast hole and apparatus of the invention for supplying liquid oxyge to the blast hole of FIGURE 1; and 7 FIGURE 4 is a horizontal section taken along the line 4 4 in FIGURE 3.

The explosive of the present invention is of the type generally known as LOX explosives and consists of a combustible material such as carbon and liquid oxygen. A large variety of ingredients has been used in these LOX explosives. The oxygen component has ranged from liquid air which contains about 21% oxygen to substantially pure oxygen and the combustible material has included wood pulp, cotton, lamp black, carbon black, chars, hydrocarbons, metal powders, sulphur and the'like.

I prefer to use carbon as the combustible material for my explosive and either activated or non-activated carbon may be used. Activated carbon is preferred because it gives faster detonation and more power. speaking, finer particle sizes of carbon give greater explosive speeds and when the carbon is non-activated, the

particle size should be very small to present the maximum.

surface area to the oxygen. When using non-activated carbon, I prefer particle sizes of the order of 400 mesh and with activated carbon, particle sizes of the order of 200 to 250 mesh are entirely satisfactory. The particle size of the carbon is not critical but the sizes mentioned give excellent results. If desired, the carbon may be eproofed with acid as described in my United States Letters Patent No. 2,723,188 but this is not necessary in the present invention. 7

According to the present invention, the combustible material is mixed with a liquid gashaving a boiling point no higher and preferably lower than that of liquid oxygen. The gas should be inert and various gases such as helium (13.1. -452 F.) could be used. However, since'liquid oxygen (B.P. --297 F.) is obtained by fractional distil- Generally tions, the combustible material, such as carbon, does not orient into flat position or become packed into a dense mass. Rather, the carbon remains loose and fluffy during the subsequent volatizat-ion of the liquified inert gas. Thus, a greater quantity ofliquid oxygenmay be introduced into the loose mass of carbon particles and more homogeneous contact between components of the explosives obtained.

As shown in FIGURE 1 of the drawing a blast hole indicated generally at It and having side walls 12 is drilled into the ground, rock or other material to be blasted. This blast hole 10 may be drilled in any suitable fashion known in the art and when the blast hole is to be drilled in very hard rock it is frequently burned into the rock by a so-called jet piercing rig. These jet piercing rigs are highly efficient for the rapid formation of blast holes but frequently the walls 12 contain pockets, recesses or faults which make it 'diflicult to load the blast hole with conventional explosives but which are conveniently and'efllectively loaded by the process of the present invention.

After the blast hole It) has been drilled a hollow conduit indicated at 16 is inserted in the blast hole. This conduit consists of-an upper portion, 18 which may be formed of suitable material such as paper, plastic, aluminum or the like, which is impervious to gas or liquid. When the material of the tube 18 is formed of combustible material it is preferably treated to make it fire retardant or fire resistant. I I

The lower portion 20 of the conduit 15 consists of a closed fabric bag which is suitably secured to the lower end of the portion 18 by a band 21 and a suitable adhesive. The bag 20 may be formed of various fabrics such as cotton, duck or'canvas, it being essential that the bag freely pass gas and liquid while preventing the passage of solid carbon particles. The bag 20 may be made fire retardant but this is not essential.

The detonator'22 is assembled with the. conduit 16 and the end of the detonator extends outward through a hole 24 in the bag 20 to a predetermined location within the explosive mass 38. This location determines to some extent the nature of the ultimate blast. Various detonators may be used but I prefer to use the commercial detonator known in the trade as Primacord and the Primacord detonator may be itself detonated to initiate the explosion by any suitable means known in the art.

' The bag 26 is preferably reinforced by a helical spring 26 which'is normally secured to the lower end of the tube 13 and extends downward to the bottom ofv the bag 2%) maintaining the bag in generally cylindrical shape.

' In order to preventcollapse of the bagfltlduring loading of the blast hole, a stall? orblock 28 is placed within the bag 20 prior to its introduction in the blast hole. It

, is essential that this staff or block 28 be recessed so as not of the detonator 22 and also to allow maximum free space for the escape of evaporating inert gas. The outer edges 32 of the staff 'or block 28 engage the helical spring 26 to maintain the bag portion 20 in substantially cylindrical form during the loading of the hole. The staffor block 28 may be formed of wood, metal or other suitable material and is ordinarily provided with a screw eye 34- so that it may be withdrawn from the hole by a rope orco'rd36.

lation of liquid air, and since this process also yields.

liquid. nitrogen (B.P. .32l F.) economy practically compels the use of nitrogen as the inert liquid gas.

According to the present invention the combustible material and liquified inert gas are mixed to formi a slurry or suspension, the ratio of the components of the mixture being about 2.5 to. 3 parts by weight of liquified inert gas to one part by weight of combustible material. 175

It has been found that with a mixture of these propor- VAfter the conduit" lohasbeen positioned in the blast hole llland whilethe reinforcingstaif 28 is still in posi- I tion in the bag 20 a mixtureof combustible material and inert gas is poured into the bast hole lldoutside of the conduit 16. This mixture normally consists of carbon and aninert gas such as nitrogen mixed'in the ratio of about two and a halfto three parts by weight of nitrogen toone part of carbon; This slurry has the consistency of; wet mortar or concrete and; is poured into the blast 7 wall 12 of the hole.

hole up to a predetermined level 4% at or very close to the junction of the impervious upper portion 18 and the bag 20 of the conduit 16. The fluid slurry fills irregularities in the walls 12 eliminating gas pockets which would cushion the explosion.

Immediately upon striking the higher temperature walls of the blast hole, the liquid nitrogen begins to volatilize into gas having a volume of 700 times the volume of the liquid itself. The low temperature of the nitrogen freezes the earth to a substantial distance outward from the hole and the high volume of gas formed blows upwardly to escape. While there is still a large supply of liquid inert gas in the hole, wet gravel is shoveled into the hole around the hollow conduit 16 and is immediately frozen into a seal 42 between the hollow conduit and the side gas tight seal, mud is shoveled into the hole on to of the frozen gravel and the mud immediately freezes to form a second layer 44 of seal between the side 12 of the blast hole and the conduit 16. The nitrogen continues to volatilize escape out through the filter bag 20, up the grooves 30 in the staif 23 and out the upper end of conduit 16.

After the gravel 42 and the wet mud 44 have been frozen to form a tight seal, sand or earth stemming material 46 is shoveled into the blast hole to fill up the hole. The tight seal formed by the gravel 42 and the mud 44 supports the weight of the stemming material 46 and there is no movement of the gravel seal 42 or mud seal 44 downwardly to compress or pack the carbon. Thus, the volume of space occupied by the mixture of carbon and nitrogen is fixed and determined. Thereafter, the stafi 28 is removed by pulling upwardly on the removing line 36.

Next, a hollow tube 48, which may be formed of fire retarded paper or cardboard or of thin metal or plastic is inserted in the conduit 16. The bottom end of the tube 48 is open and an additional aperture 50 may be provided at the bottom of the tube 48 if desired. Spacing lugs 52 are secured to the hollow tube 48 and extend outwardly into engagement with conduit 16 to center the tube in the conduit. Next, a funnel 54, also formed of metal, plastic or fire retarded paper is secured to the upper end of the tube 43 by means of a seal of frozen mud 56. A container 58 for liquid oxygen is provided in the form of an open-top cylindrical box having an outlet aperture 59 surrounding the conduit 16.

The upper end of conduit 16 extends through the aperture 59 in container 58 and a frozen mud seal 62 forms a liquid tight seal between the two. A polyethylene bag 64 may be placed in the container 58 as a liner if desired. Liquid oxygen is then poured into the container 58 up to the level 66. The cold liquid oxygen flows down through the duct 48 and out through the lower end of duct 48 and through aperture 50. The liquid oxygen, being at a temperature not substantially below its boiling point, raises the temperature of the liquid nitrogen to its boiling point by heat transfer. Liquid oxygen also passes down the passage between the duct 48 and the conduit 16 and through the filter bag 20 into contact with the liquid nitrogen mixed with carbon. The nitrogen is volatilized as the liquid oxygen enters the system and the nitrogen escapes as a gas through the filter bag 20 and bubbles up through the passage between the duct 48 and the conduit 16.

Liquid oxygen explosives have one inherent difiiculty in that the liquid oxygen continues to vaporize in the hole and it is often dificult to determine whether or not the hole is fully loaded. The maximum explosive force is obtained When the amount of liquid oxygen in intimate contact with the carbon is approximately 2.66 parts of oxygen to 1 part of carbon. When a large field is to be blasted with a multiplicity of blast holes, there is always a time delay in loading the various holes and the present invention provides a simple and effective way for in- In order to form a more perfect 7,

6 dicating that the blast holes are fully loaded and also provides a method of maintaining the blast holes in fully loaded condition for an indefinite period of time.

When the liquid oxygen is first introduced into the container 58 and funnel 5 4, the level 66 will drop fairly rapidly due to the oxygen replacing the nitrogen and there will be fairly violent bubbling of nitrogen around the funnel 54. After the oxygen has fully replaced the nitrogen, the level 66 will drop less rapidly and the bubbling will be less violent. So long as liquid oxygen is visible in the container 58 or funnel 54 the operator can tell at a glance that the hole is fully loaded and the hole may be maintained in this loaded condition for an indefinite period of time by supplying additional liquid oxy gen.

It will be seen that the invention provides a composition of liquified inert gas and combustible material having critical proportions to maintain the combustible material loose and fluffy for later mixture with liquid oxygen.

It will also be seen that the invention provides methods and apparatus for accomplishing the loading of a plurality of blast holes with LOX explosives where the liquid oxygen may be introduced simultaneously with the volatilization of the liquified inert gas and the level of the liquid oxygen subsequently observed during the passage of time before detonation.

The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiment is therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

What is claimed and desired to be secured by the United States Letters Patent is:

1. A method of loading a blast hole with a liquid oxygen combustible material type explosive which comprises, forming a suspension of a finely divided mass of carbon in liquified nitrogen having a boiling point not substantially higher than that of oxygen, said suspension comprising from about 2.5 to about 3 parts by weight of liquified nitrogen to one part by weight of carbon, introducing the suspension into the blast hole, permitting some of said liquified nitrogen to vaporize, introducing liquid oxygen into the blast hole and into the carbon, while at the same time permitting the remainder of said liquified nitrogen to vaporize and escape from said blast hole.

2. A method of loading a blast hole with a liquid oxygen combustible material type explosive which comprises, forming a suspension of a finely divided mass of carbon and liquefied nitrogen having a boiling point below that of oxygen, the ratio of the components of said suspension being from 2.5 to 3 parts by weight of liquified nitrogen to one part by weight of carbon, introducing the suspension into the blast hole, permitting some of said liquified nitrogen to vaporize, introducing liquid oxygen into the blast hole and into the carbon, while at the same time permitting the remainder of said liquified nitrogen to vaporize and escape from said blast hole.

3. A method of loading a blast hole with a liquid oxygen combustible material explosive, which comprises inserting a hollow conduit having a liquid-pervious solidimpervious lower portion and an impervious upper portion into said blast hole so that the lower extremity of said hollow conduit lies adjacent the bottom of said blast hole and the upper extremity of said hollow conduit lies adjacent the top of said blast hole, partially filling the hole to a point above said lower portion of said conduit with a mixture of particles of combustible material and a liquified inert gas having a boiling point not substantially higher than the boiling point of oxygen, introducing a freezable sealing material above said mixture over the portion of said hole between the outer surface of said hollow conduit and the side of said hole, permitting said freezable sealing material to freeze and form a liquid impervious gas-impervious seal across the portion of said hole between the outer surface of said hollow conduit and the side of said hole, inserting a hollow duct down said hollow conduit to position an opening at the lower end of said duct adjacent the bottom of said blast hole, and flowing liquid oxygen down said hollow ,duct and said hollow conduit and through said liquid-pervious lower portion of said hollow conduit to cause the vaporization of said liquified inert gas and escape thereof through said 1iquid-pervious lower portion of said hollow conduit and upwardly through the space between said hollow duct and said hollow conduit,

4. A method of loading a blast hole as set forth in claim 3, wherein said fr ee zable sealing material includes a lower layer of wet gravel and an upper layer of a material selected from the group consisting of mud and clay.

5. A method of loading a blast hole as set forth in claim 3 wherein the ratio of the components of said suspension is from 2.5 to 3 parts by weight of liquified nitrogen to one part by weight of carbon.

6. A method of loading a blast hole with a liquid oxygen combustible material explosive, which comprises inserting a removable stafi into the flexible lower portion of a hollow conduit having a liquid-pervious solid-impervious flexible lower portion and an impervious upper portion, inserting said hollow conduit and said stall into said blast hole so that the lower extremity of said hollow conduit lies adjacent the bottom of said blast hole and the upper extremity of said hollow conduit lies adjacent the top of said blast hole, introducing into the portion of said hole between said hollow conduit and the side of said hole a mixture of particles of combustible material in a liquified inert gas having a boiling point lower than that of oxygen to fill the hole to a point above said lower portion of said conduit, introducing a freezable sealing material above said mixture over the portion of said hole between the outer surface of said hollow conduit and the side of said hole, permitting said freezable sealing material to freeze and form a liquid-impervious gas-impervious seal between the hollow conduit and the side of said hole, removing said stall from said hollow conduit, inserting a hollow duct down said hollow conduit to position an opening at the lower end of said duct adjacent the bottom of said blast hole, securing the rim of an outlet aperture of a container for liquid oxygen to the-upper end of said hollow conduit with a frozen mud seal, securing a tunnel to the upper end of said hollow duct with a frozen mud seal, and introducing liquid oxygen into said container to flow down said funnel and said hollow duct and said hollow conduit and through said liquid' pervious lower portion of said hollow conduit to cause the vaporization of said liquified inert gas and escape thereof through said liquid-pervious lower portion of said hollow conduit and upwardly through the space between said hollow duct and said hollow conduit.

7 An apparatus positioned in a blast hole for use in loading said blast hole which comprises a hollow conduit having an open upper end and a closed lower end, said hollow conduit being positioned in a downwardly directed blast hole, said blast hole having an open upper end and a closed lower end, the upper portion of said hollow conduit being liquid and gas impervious, the lower portion of said hollow conduit being a flexible fabric, bag, said bag being liquid and gas pervious and solid-impervious, a removable staff of rigid material within said hollow conduit and extending over at least said lower portion thereof, said stall holding said flexible bag in an extended position in a directon toward the lower end of said last hole, and means secured to the upper end of said staff forremoving said staff from said conduit.

8. An apparatus as set forth in claim 7 wherein the flexible bag encloses a helical spring within s'aid bag ex 8 tending from said upper portion of said hollow conduit to the lower end of said flexible bag.

9. An apparatus positioned in a blast hole for use in loading said blast hole which comprises a hollow conduit having an open upper end and a closed lower end, said hollow conduit being positioned in a downwardly directed blast hole, said blast hole having an open upper end and a closed lower end, the upper portion of said hollow conduit being rigid and liquid and gas impervious, the lower portion of said hollow conduit being a flexible fabric bag, said bag being liquid-and gas-pervious and solid-impervious, a hollow duct extending through said hollow conduit and spaced therefrom, said duct having at least one opening adjacent the lower end of said hollow conduit, a storage container for liquid oxygen having an outlet aperture secured to the upper end of said hollow conduit, and a funnel secured to, the upper end of said hollow duct within said container.

10. A method of loading a blast hole with a liquid oxygen combustible material explosive, which comprises inserting a hollow conduit having a liquid-pervious solidimpeivious lower portion and an impervious upper portion into said blast hole so that the lower extremity of said hollow conduit lies adjacent the bottom of said blast hole and the upper extremity of said hollow conduit lies adjacent the top of said blast hole, partially filling the hole to a point above said lower portion of said conduit with a mixture of particles of combustible material and a liquified inert 'gas' having a boiling point not substantially higher than the boiling point of oxygen, introducing a sealing material above said mixture over the portion of said hole between the outer surface of said hollow conduit and the side of said hole to form a liquid impervious gas-impervious seal across the portion of said hole between the outer surface of said hollow conduit and the side of said hole, inserting a hollow duct down said hollow conduit to position an opening at the lower *end of said duct adjacent the bottom of said blast hole,

and flowing liquid oxygen down said hollow duct and said hollow conduit and through said liquid-pervious lower portion of said hollow conduit to cause the vaporization of said 'liquified inert gas and escape thereof through said liquid-pervious lower portion of said hollow conduit and upwardly through the space-between said hollow duct and said hollow conduit.

11. An apparatus positioned in a blast hole for use in loading said blast hole which comprises a hollow conduit having an open upper end and a closed lower end, said hollow conduit being positioned in a downwardly directed blast hole, said blast hole having an open upper end and a closed lower end, the upper portion of said hollow conduit being rigid and liquid and gas impervious, thelower portion of said hollow conduit being a flexible fabric bag, said bag being liquid and gas-pervious and solid-impervious, a hollow duct extending through said hollow conduit and spaced therefrom, said duct having at least one opening adjacent the lower end of said hollow conduit.

'12. An apparatus positioned in a blast hole for use in loading said blast hole which comprises a hollow conduit havin antopen upper end and a closed lower end, said hollow conduit beingpositioned in a'downwardly directed blast hole, said blast hole having an open upper in adirection toward the lower portion of said blasthole,

said bag being liquid and gas pervious and solid impervious.

13. A blast hole containing a carbon-liquid nitrogen slurry in' the lower portion thereof, 'a hollow conduit having an open upper and a closed lower end, the upper portion of said' hollow conduit being rigid and liquid and gas impervious, the lower portion of said hollow conduit being liquid and gas pervious and solid impervious, said conduit extending within said blast hole, a hollow duct extending through said conduit member and spaced therefrom, said duct having at least one opening adjacent the lower end of said hollow conduit, a container having a supply of liquid oxygen therein and having an outlet aperture secured to the upper end of said hollow conduit, a funnel secured to the upper end of said hollow duct, said funnel being mounted within said liquid oxygen container and spaced from the outlet aperture of said liquid oxygen container.

References Cited in the file of this patent UNITED STATES PATENTS 1,282,229 Haynes et a1. Oct. 22, 1918 10 Berman May 15, 1928 Vollez Nov. 6, 1928 Tilbury et a1 June 9, 1936 Costello Dec. 14, 1937 Wahlin Feb. 9, 1954 Allen Nov. 9, 1954 Barlow Mar. 22, 1955 Barlow Nov. 8, 1955 Aitchison et al. May 15, 1956 Johansson Feb. 25, 1958 FOREIGN PATENTS Great Britain 19 15 Great Britain Mar. 2, 1955 

2. A METHOD OF LOADING A BLAST HOLE WITH A LIQUID OXYGEN COMBUSTIBLE MATERIAL TYPE EXPLOSIVE WHICH COMPRISES, FORMING A SUSPENSION OF A FINELY DIVIDED MASS OF CARBON AND LIQUEFIED NITROGEN HAVING A BOILING POINT BELOW THAT OF OXYGEN, THE RATIO OF THE COMPONENTS OF SAID SUSPENSION BEING FROM 2.5 TO 3 PARTS BY WEIGHT OF LIQUIFIED NITROGEN TO ONE PART BY WEIGHT OF CARBON, INTRODUCING THE SUSPENSION INTO THE BLAST HOLE, PERMITTING SOME OF SAID LIQUIFIED NITROGEN TO VAPORIZE, INTRODUCING LIQUID CXYGEN INTO THE BLAST HOLE AND INTO THE CARBON, WHILE AT THE SAME TIME PERMITTING THE REMAINDER OF SAID LIQUIFIED NITROGEN TO VAPORIZE AND ESCAPE FROM SAID BLAST HOLE. 